Recommended

Minimum

Pricing

An important factor to consider is how much battery life you’ll need on your laptop. No matter how much battery you have, using your built-in DVD drive a lot and having a 17″ screen will drain it faster. Battery technology–just like any technology–is improving all the time.

Yesterday’s laptops featured Ni-Cad (Nickel-Cadmium) batteries, which poisoned the environment when disposed of improperly, didn’t offer much up-time (comparatively), and had the annoying habit of remembering how long you had used them and refusing to work any longer the next time. Then there were NiMH (Nickel-Metal-Hydride) batteries; they offered longer life, better efficiency, and no memory problems.

The current generation of laptops still uses Lithium Ion batteries. These batteries offer a gain in efficiency over NiMH batteries, with an extremely low discharge rate (long shelf life when charged) and efficiency improvements over Lithium Ion batteries; movement towards new battery technology has slowed, however. Even though improvements are made, we are getting to the point where packing so much energy into a tiny space is getting a bit dangerous. If you’ve ever seen news footage of a laptop computer igniting, that’s what could happen if the battery goes haywire. Don’t be too worried about it, though, as that is an extremely rare event. A single fire typically causes thousands of batteries to get recalled, though, since there is little room for error where a burning laptop is concerned.

Some laptops claim up to 5 hours worth of up-time on one battery–take this figure with a grain of salt. That’s probably how long the battery would last if you put on the blank-screen screen saver and didn’t touch it for 5 hours. Expect more in the range of two or three hours per stock battery under continual use. If you plan to be on flights, trains, or buses for 10 hours at a time, buy some extra batteries, make sure you have a power plug handy, or make sure you get a model that has a nice add-on battery feature that can hold a lot of juice.

Some designs offer a battery plate that fits on the bottom of the laptop, adding size and a few pounds but offering many more hours of battery life. If that’s what you need, check around for interesting battery setups. Several manufacturers also offer laptops with expansion slots that will accept a variety of peripherals, including a second battery–that second battery can double your battery life. If your laptop doesn’t offer that, you have to buy another of the same battery and may want to make sure you get a battery charger to go with it so that you can charge both batteries at the same time (one in the laptop, one in the charger). Obviously, that is not ideal. If you need it, just go for a model that offers the battery capacity you want. Also, keep in mind that extra batteries can cost up to and over US$200 apiece.

When selecting a battery, manufacturers will often list an amount of “cells,” where each cell has a certain capacity; thus a 9 cell has 50% more capacity than an equal model 6-cell battery. That is useful for comparing directly, but the story is more complex if you wanted to compare different batteries on different laptops. Batteries have a voltage rating (V) and milli-Amp hours (mAH), which, if multiplied together, give you milliwatt hours. For example, a 14.8 V battery with 4460 mAH gives you 66,000 milliwatt hours (66 watt-hours). You can compare batteries this way, but also keep in mind that different laptops have very different power requirements that vary based on the components and how well the operating system manages power consumption. Typically, bigger, heavier batteries will give you a higher watt-hour rating. A 6-cell battery may be the same form factor as a 9-cell, but the 6-cell will weigh less since there’s less chemical in it to hold onto that charge.

If you are a mobile warrior, you will want the most cells and/or most watt-hours you can get into your model so you can go 5 or 6 hours without a recharge. It is so painful to run our of power before you are ready.

Recommendations
Make sure you get a Lithium Ion battery with maximum cells in the model you are looking for, including a spare add-on battery that replaces a DVD-drive or otherwise adds onto the battery that comes standard. NiMH or, even worse, Ni-Cad are old technologies that are best forgotten when it comes to powering laptops, although they are still used to power your electric tools.